Deepwater Corals Thrive at the Bottom of the Ocean, but Can’t Escape Human Impacts

When people think of coral reefs, they typically picture warm, clear waters with brightly colored corals and fishes. But other corals live in deep, dark, cold waters, often far from shore in remote locations. These varieties are just as ecologically important as their shallow water counterparts. They also are just as vulnerable to human activities like fishing and energy production.

Earlier this year, I was part of a research expedition conducted by the Deep Search project, which is studying little-known deep-sea ecosystems off the southeast U.S. coast. We were exploring areas that had been mapped and surveyed by the U.S. National Oceanic and Atmospheric Administration’s research ship Okeanos.

In an area 160 miles off South Carolina we deployed Alvin, a three-person research submersible, to explore some features revealed during the mapping. What the scientists aboard Alvin found was a huge “forest” of coldwater corals. I went down on the second dive in this area and saw another dense coral ecosystem. These were just two features in a series that covered about 85 miles, in water nearly 2,000 feet deep. This unexpected find shows how much we still have to learn about life on the ocean floor.

Organisms that live in deep, cold waters grow slowly, mature late and have long lifespans. Deep-sea black corals are among the oldest animals on earth: One specimen has been dated at 4,265 years old.